In such a type of recording medium or a recording-reproducing system utilizing this medium, information recorded on a holographic recording medium can be reproduced by irradiating reading light on the same position and at the same angle as in reference light. In this case, since the incident conditions of the reading light must be exactly the same as that of the reference light at recording time, tracking and focusing must be performed for irradiating the same position on the recording medium with laser light radiated from a light source for recording-reproducing. Therefore, servo information or address information for detecting the recording position must be recorded on the recording medium.
For example, Japanese Patent Laid-Open Publication No. 2002-109758 discloses a recording medium in which a reflection surface having concavities and convexities is provided in the lower side of a recording layer. This reflection surface is designed so as to reflect position adjustment light from a light source for position adjustment but to allow signal light and reference light from a light source for recording to pass through. Thus, the relative position between the light source for recording and the recording medium is adjusted based on the intensity of the light obtained by reflecting, from the reflection surface, the position adjustment light different from the signal light and the reference light.
Also, for example, the publication of Japanese Patent No. 2636563 discloses a recording medium in which regions for recording signals for position adjustment are provided adjacent to data regions in a recording layer of the recording medium.
In the case of the above recording medium of Japanese Patent Laid-Open Publication No. 2002-109758, since the light reflected from the total reflection type surface having projections and depressions is utilized, servo light has an effect on the recording layer. Therefore, a problem arises that noise becomes large upon recording-reproducing.
Also, in the case of the above recording medium disclosed in the publication of Japanese Patent No. 2636563, the data regions are narrowed, resulting in a problem that storage capacity is reduced.